Which are the conjugate base of strong acid HClO_4, H_2SO_4, HNO_3 and H_3PO_4 ? It is strong or weak ?

Which are the conjugate base of strong acid HClO_4, H_2SO_4, HNO_3 and

1.	Which are the conjugate base of strong acid HClO_4, H_2SO_4, HNO_3 and H_3PO_4 ? It is strong or weak ?
Answer» SOLUTION :`ClO_4^(-) , HSO_4^(-), NO_3^(-)`and `H_2PO_4^(-)` all are CONJUGATE BASE of STRONG ACID